several years ago at the Sportsman's Show in Minneapolis there was a guy selling yokes to convert the wheel on a trailer jack to use your spare tire as the wheel. thus the jack became the spare tire carrier and when you wanted to roll your trailer around it was using a 12 in tire and wheel that doesn't sink in to soft ground or fall in every little hole. this was back when exhibit space wasn't so expensive that the small independent guy could acually afford to be an exhibitor. i've talked to a couple of RV places that sort of remember such a trailer jack but have no idea of where to get one. does anybody know of anyone manufacturing such a jack or jack conversion?